Sump pumps are one of the most boring parts of home ownership. Until that one storm comes and suddenly they’re interesting.
After losing power one time this summer, I got paranoid and decided to build a battery backup. Home Depot had the basement watchdog systems, but they seemed high maintenance and I wanted something that would let me be lazier. I went with a LifePo4 battery system, that will (hopefully) get me 10 to 15 years. The battery charger has a float/storage mode so it can stay on 24/7. Doing some test runs, I think I can get about 400 cycles out of the battery before it hits 0%. I added some additional safety features (DC circuit breaker, GFCI with auto-on, Lithium fire extinguiser, etc), and added some battery powered lights and a basket of hand tools, so in the event the power goes out in the dead of night, something goes wrong, and I have to get my feet wet, everything is there ready to go.
Jesus, you know they make 120 v sumps with a 12v backup right? :)
Indeed they do. But I’m lazy. I’ll explain:
The systems with the 12v backups only activate said backup when the main pump fails, typically due to a power outage. So if you live in an area with consistent power, the backup will hardly ever activate. Over time the backup atrophies due to never cycling and then when your main does fail, the backup is also dead too. Then you’re fucked.
To fix this, they recommend going down and unplugging your main, and running a hose or something to your pit to test the backup every 12 months or so, making sure it works. But who wants to do that.
With my system, I have a pump alternator (silver box, bottom left in pic). So I have two primary pumps, and it flips between 'em. So each pump runs half as often as normal. If one pump fails, the alternator flips to the other one and triggers an alert. This alert emails me saying “yo something is fucked up with the pump”, and from there I have to diagnose and fix it. But it’s asynchronous and I don’t have to worry about it until I get that email. Only thing I really need to check on an annual basis is the battery health, which is bluetooth’d to my phone.
If your sump pump moves any amount of water consistently you could automate it with your home assistant (or whatever because I see the zooz high power switches). Just automate the switch to go off and monitor the other one. You could even have it run every month or something.
I’m using them to monitor via Grafana
Honestly very cool setup. I’d love something like this if I get a house that needs a sump.
Basement watchdog brand. 12v activates on a higher water level. they both use the same output line. There’s a test button you can use to test the 12v if youwant, but the instructions do not reccomend “exercising” the 12v pump. https://basementwatchdog.com/wp-content/uploads/2025/06/CITE-33-US-manual-05-15-25-Web.pdf
So the Watchdogs are legit systems and I won’t dog on them (har har).
That said, for myself, I wanted a LifePo4 system. The Watchdogs are AGM. Additionally, with Watchdog you are putting all your eggs in one basket, and you really gotta swap the whole thing if one part fails other than the battery.
They do have the advantage of being ubiquitous, and most plumbers know them well, so it’s easy to hire help if you need it.
You do need to replace both pumps if one fails. but… it does have 2 independent pumps. If the power goes out, or the primary fails, you’re still dry.
More importantly, the upside to your setup, the lead acid / AGM batteries on mine need to be replaced every 3-4 years, your battery will likely last many years.
The downside, you have a long dependency chain with a number of single points of failure.
to each their own.
It’s the same number of points of failure. The watchdogs have an automatic transfer switch, a power inverter, a fuse or circuit breaker, etc - it’s just all embedded in a single box instead of being parted out.
Watchdog can lose all things out of one of the following lines and still run, and it will let you know if either line fails with an audible alarm.
120v->Fuse->120v motor->120v impeller->120v float
or
12v battery -> 12v Fuse -> 12v motor->12v float
The only shared point of failure would be a crack or hole in the exit line
The 12 and 120 sides are completely seperate except the water exit path.
The 120v side doesn’t get anything from the “control box,” it’s just a float pump.
If you filled the some faster than the 120 could pump, they’d both run at the same time. (and it would complain audibly about it)
Gotta love showing off your great work and someone coming in with “UM AKSHULLY THIS IS BETTUR”
There’s a lot of variables involved in sump pump systems. I don’t have any qualms with rumba’s comments, they’ve added to the conversation.
If you’re on city water that doesn’t lose pressure during power outages they also make water powered sump pumps.
Venturi pumps are awesome, but with the risk of basement flooding, i’ve never trusted them enough. the risk of no flow+power out is low, but not zero. I have a 12v bilge pump and a float in a tackle box for emergencies and 2 cars of fully wokring 12 batteries :)